1. Field of the Invention
This invention relates to knitted reinforcement fabrics used for tubular elastomeric articles such as hoses for fluid conveyance or fiber-reinforced composite structures.
2. Description of Related Art
European patent number EP1780458B1 to Guo describes a pipe having a textile reinforcement presented in a form of a knit fabric which is formed of two threads having different rigidities so as to form mixed knots with a rigid thread and a less rigid thread in contact with each other. One thread is made of aromatic polyamide e.g. polyparaphenylene terephthalamide, and the other thread is made of aliphatic or aromatic polyamide e.g. polyamide 6.6 or copolymer of polyparaphenylene terephtalamide and 3, 4′-oxydiphenylene terephthalamide.
United States patent application publication number 2013/0327433 to Litchfield et al discloses a knit fabric suitable as a reinforcement for elastomeric articles comprising a plurality of reinforcement yarns wherein each course of the fabric comprises either a first or second yarn, the modulus of the first yarn being different from the modulus of the second yarn, and the courses comprising the first and second yarns are arranged in one of the following sequences, (a) alternating courses comprise first and second yarns respectively, (b) the courses form a repeat pattern of, in order, a course comprising a first yarn, two courses comprising a second yarn and a course comprising a first yarn or (c) the courses form a repeat pattern of, in order, a course comprising a second yarn, two courses comprising a first yarn and a course comprising a second yarn.
German publication DE 10 2013 019 392 to Matsumoto describes a method involving inducing a thread guide that supplies a knitting yarn that is knitted in a reverse direction. Another thread guide is introduced in travelling direction against the set direction. A redundant knitting yarn end is arranged in proximity of the former thread guide. A crossover yarn is connected with a base-knit-portion by the latter thread guide, and crosses the redundant knitting yarn end of a loop board. A pair of needle beds is extended in a transverse direction and arranged facing each other in longitudinal direction.
U.S. Pat. No. 7,572,745 to Branch et al discloses a flexible hose comprising a tube, a knit fabric, and a cover. The knit fabric comprises a hybrid yarn which comprises a first yarn of co-para-aramid fibers and a second yarn of meta-aramid fibers. The hose exhibits significantly improved burst pressure and/or improved impulse fatigue resistance.
There is an ongoing need to provide knitted fabrics of improved mechanical strength that can enhance the properties of articles comprising the fabric, for example to increase the pressure carrying capability of a rubber hose while maintaining a simple and cost effective one-step production method.